Compreshension-II
In non-ideal solutions, at one of the intermediate compostions, the total vapour pressure is highest and the boiling point is lowest. At this point, the composition of the liquid and vapour phase is same. So, if liquid mixture vapouriese at this point and vapours are condensed, teh condensate contains same compositon as present in original liquid mixture. it means at this point liquid behaves like a pure liquid and is called an Azeotropic mixture.
Which of the following cannot form low boiling point azeotrope ?

Options

A. n-heptane & n-hexane
B. Acetone & aniline
C. Both (1) & (2)
D. `CHCl_(3) & C_(2)H_(5)OH`

Answer

To solve the question regarding which of the following substances cannot form a low boiling point azeotrope, we will analyze the given options based on their chemical properties and the concept of azeotropes.

### Step-by-Step Solution:

1. **Understanding Azeotropes**:
- An azeotropic mixture is a mixture of two or more liquids that has a constant boiling point and composition throughout the distillation process. Azeotropes can be classified as low boiling point or high boiling point azeotropes based on their boiling points relative to the pure components.

2. **Analyzing the Options**:
- We have the following options to consider:
- a) n-heptane
- b) n-hexane
- c) Acetone and Aniline
- d) Chloroform and Ethanol

3. **Option a: n-heptane and Option b: n-hexane**:
- Both n-heptane and n-hexane are alkanes. Alkanes typically form ideal solutions because they have similar molecular structures and interactions. Ideal solutions do not exhibit significant deviations in vapor pressure from Raoult's Law, hence they do not form azeotropes, especially low boiling point azeotropes.

4. **Option c: Acetone and Aniline**:
- Acetone is a ketone, and Aniline is an amine. The presence of the amino group in Aniline allows it to form strong hydrogen bonds. This interaction can lead to negative deviation from Raoult's Law, which typically results in a higher boiling point rather than a low boiling point azeotrope.

5. **Option d: Chloroform and Ethanol**:
- Chloroform and Ethanol can form a low boiling point azeotrope due to the strong hydrogen bonding between the hydroxyl group of ethanol and the chlorine atom of chloroform. This interaction can lower the boiling point of the mixture.

6. **Conclusion**:
- Based on the analysis, both n-heptane and n-hexane (Options a and b) cannot form low boiling point azeotropes due to their ideal solution behavior. Additionally, Acetone and Aniline (Option c) also do not form low boiling point azeotropes due to the strong hydrogen bonding leading to higher boiling points.

### Final Answer:
The substances that cannot form low boiling point azeotropes are:
- n-heptane
- n-hexane
- Acetone and Aniline

Thus, the correct answer is both options a and c.